A multiplicity of devices and analytical methods have been developed in an attempt to obtain fast and accurate quantitative analysis of a vast array of products which are manufactured subject to strict control of moisture. For example, certain products have a specific range of moisture which dictates the taste and/or texture of the product. Thus, once the consumer associates a specific taste and/or texture to the product the uniformity of that taste and/or texture becomes a hallmark to the product's long term acceptance and ultimate success. Furthermore, moisture content is a specific process control in food processing, waste water treatment and materials processing.
Typically, these products require the volatilization of moisture or the like from the substance for moisture determination. In recent years, conventional microwave heating has been employed in the methods to remove various volatiles such as moisture followed by calculations of the amount of moisture lost. Conventional microwave heating requires the use of high power levels for providing effective drying due to the conventional microwave oven's employing random direction Te waves as the dominant energy field for the drying process. As a result, these microwave ovens produce hot and cold spots, over heating edges and charring of the products being analyzed. In addition, these conventional microwave ovens failed to provide a satisfactory solution which provided fast and accurate moisture determination of the product without the degradation of the product due to these problems.
Thus, there continues to be a need for an efficient microwave moisture analyzer which offers uniformity of microwave heating and rapid moisture determining analysis without the degradation of the product due to these problems. This is particularly important in light of the fact that most of the testing of products is related to process control in some form or another. Thus, the speed of the analysis and tests are hallmarks of high quality mass production. In addition, there is a need for a microwave moisture analyzer which provides timely feedback for maintaining tight tolerances of both the process and product produced thereby. Furthermore, a microwave moisture analyzer is needed which includes automated functions which simplify routine analysis thereby substantially eliminating the dependency of the result of the analysis on the skill and care exercised by the operator.
In addition, scales have been employed within these conventional microwave ovens to measure the weight of the product being analyzed. However, these devices have heretofore been susceptible to jarring and vibration in the working environment which resulted in anomalous weight readings. Such inconsistencies in operation result in unpredictable and unreliable moisture determination of the product.
Furthermore, none of the prior art which applicant is aware addresses the problem of continuing to dry the product after all of the moisture has been exhausted therefrom. This of course alters the mass which introduces an error in the final moisture calculation. Moreover, none of the prior art which applicant is aware addresses the possibility of a sample igniting in the chamber while doing a loss on drying process. Although the possibility of a sample igniting in the chamber while doing a loss on drying process is low, it does exist.
Therefore, not only does there continue to be a need for an efficient microwave moisture analyzer which offers uniformity of microwave heating and timely feedback for maintaining tight tolerances of the drying process, there also continues to be a need for a microwave moisture analyzer which is impervious to vibration and jarring and which addresses the problem of over drying the product and the possibility of the product igniting in the analyzer.
The following prior art reflects the state of the art of which applicant is aware and is included herewith to discharge applicant's acknowledged duty to disclose relevant prior art. It is stipulated, however, that none of these references teach singly nor render obvious when considered in any conceivable combination the nexus of the instant invention as disclosed in greater detail hereinafter and as particularly claimed.
U.S. Pat. No.ISSUE DATEINVENTOR3,909,598Sep. 30, 1975Collins, et al.4,106,329Aug. 15, 1978Takahashi, et al.4,165,633Aug. 28, 1979Raisanen4,168,623Sep. 25, 1979Thomas, Jr.4,193,116Mar. 11, 1980Funk4,276,462June 30, 1981Risman4,291,775Sep. 29, 1981Collins4,312,218Jan. 26, 1982Eckles4,316,384Feb. 23, 1982Pommer, et al.4,390,768Jun. 28, 1983Teich, et al.4,398,835Aug. 16, 1983Athey, et al.4,413,168Nov. 1, 1983Teich4,438,500Mar. 20, 1984Collins, et al.4,457,632Jul. 3, 1984Collins, et al.4,554,132Nov. 19, 1985Collins4,565,669Jan. 21, 1986Collins, et al.4,566,312Jan. 28, 1986Collins, et al.4,566,804Jan. 28, 1986Collins, et al.4,651,285Mar. 17, 1987Collins, et al.4,681,996Jul. 21, 1987Collins, et al.4,749,054Jun. 7, 1988Virtanen, et al.4,750,143Jun. 7, 1988Heitz, et al.4,753,889Jun. 28, 1988CollinsRe. 32,861Feb. 7, 1989Collins, et al.4,835,354May 30, 1989Collins, et al.4,838,705Jun. 13, 1989Byers, Jr. et al.4,861,556Aug. 29, 1989Neas, et al.4,882,286Nov. 21, 1989Neas, et al.4,946,797Aug. 7, 1990Neas, et al.5,211,252May 18, 1993Henderson, et al.5,215,715Jun. 1, 1993Haswell, et al.Re. 34,373Sep. 7, 1993Collins, et al.5,318,754Jun. 7, 1994Collins, et al.5,420,039May 30, 1995Renoe, et al.5,632,921May 27, 1997Risman, et al.